Trane RTCA 108-216 Installation And Operation Manual page 31

Maintenance
and oil- line shutoff valve, without
the need to pull a vacuum on this
small volume. If the oil has been in
an open container or is otherwise
contaminated, then this small
volume must be subject to vacuum
as well. However, the filter cavity is
full of oil. Therefore, be sure to use a
flash tank in line with the vacuum
pump to ensure that the oil that is
pulled out of the filter cavity does
not slug the vacuum pump.
RLC-SVX03A-E4 31